We plan to continue the development of methods which will be generally applicable in the synthesis of macrolides, including the prototypes of the major subclasses within the group, partly in the hope that the presently obscure relationships between chemical structure and physiological activity in this important group might be elucidated. In the immediate future we shall be mainly concerned with improvement of the methods we have developed for a formal synthesis of erythromycin. We shall then proceed to complete the total synthesis of erythromycin.